In general, we believe that Kohala Ranch Water is good. The water company is supposed to provide an annual report to consumers on water quality, so ask for this information if you don't receive it.
That report does not, however, include information on chloride levels. This is the contaminant we're most interested in, since it gives a clue to how thoroughly the supply of fresh water is being utilized. If we start overpumping vis-a-vis the supply, chloride levers will rise.
The acceptable level of chloride in drinking water is considered to be 250 parts per million (or milligrams per liter). This is based on the level at which the chloride can be tasted, not on controlled health studies. Kohala Ranch water has always been well below this level. The most recent reading we have seen for chloride is 79 and 73 ppm for the two production wells.
We are, however, beginning to wonder whether this level could be affecting plant health. According to a website from North Carolina State University, 71 ppm is the acceptable limit for greenhouse use. If you have orchids or other plants that are not doing well you might consider obtaining low chloride water to see if that solves the problem. Leaves seem to be espeically sensivite to chlorides, so it might be advisable to use water from another source if you will be spraying it onto your plants. Most plants have much higher chloride tolerances.
Kohala Ranch water is also relatively high in silicon, and we wonder if that might be contributing to the hard mineral residue we see in places where water stands and evaporates.